The present invention relates to an electricity distribution network for a motor vehicle, suitable for use, for example, to power electrical equipment on board motor vehicles such as cars, trucks, . . . .
A conventional type of electricity distribution network for a motor vehicle generally comprises a battery connected to equipment on board the vehicle. The battery is thus connected to an alternator so as to be recharged by the alternator, and to pieces of equipment that consume electricity so as to power them. Common examples of such pieces of equipment comprise in particular the starter, the ignition system, the heater or air conditioner, lighting elements such as headlights, electric motors for driving windscreen wipers, windows, fans, . . . .
In the automotive industry, more and more high-power electronic circuits are being used. Such circuits include proposed electromagnetic actuators for valves, i.e. circuits that operate in pulse mode with sudden changes in the amount of power they draw.
The use of such circuits presents consequences for the network. Thus, it is necessary for the network to present resistance that is low enough to limit losses by the Joule effect. In order to limit the effects of current spikes, decoupling capacitors are associated with the circuits and/or the battery so that the network then has a relatively large amount of distributed capacitance. In addition, because of the size and the location of the conductors of the network, the network presents a relatively large amount of inductance.
The network thus constitutes an oscillating circuit of the xe2x80x9cRLCxe2x80x9d type. Current spikes drawn by circuits operating in pulse mode then run the risk of setting the network into resonance which will overload the battery and the decoupling capacitors, with this happening particularly easily when the circuits operate at an excitation frequency close to the resonant frequency of the network. Such overloading harms the reliability of the battery and the capacitors and can lead to them deteriorating.
An object of the invention is to provide a distribution network that is reliable and of low cost and that includes at least one circuit operating in pulse mode.
To this end, the invention provides an electricity distribution network for a motor vehicle, the network having at least two pieces of equipment connected to a storage battery, at least one of the pieces of equipment operating in a pulse mode likely to create oscillations in the network at a resonant frequency thereof, the network including at least one resistive element and capacitor that are associated in series and that are of resistance and capacitance determined so that the resistance of the resistive element is equal to a damping resistance for the network.
The resistive element can then damp the oscillations of the network which therefore does not enter into resonance, thus limiting the risks of the storage battery and the other elements constituting the network being overloaded. Since the capacitor prevents the DC component of the electricity carried by the network from passing through the resistive elements, Joule effect loses in the resistive element are limited.
Preferably, the resistive element and the capacitor are connected between terminals for connecting the piece of equipment that operates in pulse mode to the network.
The resistive element and the capacitor may then be integrated in the circuit of the equipment that operates in pulse mode. As a result, this equipment can be connected to the network without there being any need to modify its architecture.
Advantageously, the resistive element and the capacitor form a damping circuit located close to an end of the network, and preferably the network has a plurality of damping circuits, each adjacent to an end of the network.
Damping is then particularly effective.